Question

A diploid human cell normally has 23 pairs of homologous chromosomes, but as a woman ages, the chances of nondisjunction increase. Imagine that a gamete is produced in which the two homologues of chromosome 21 have failed to separate. If the gamete is fertilized with a normal sperm, the embryo’s cells will contain _______ chromosomes.a. 23

b. 24
c. 46
d. 45
e. 47

Answer 1

e. 47

Step-by-step explanation:

The situation is called Regular Trisomy 21. Its associated with with Down's syndrome. This is due to uneven division of the chromosomes (non-disjunction) at either the first or the second meiotic division, in either parent.

In this case, the individual has an extra chromosome 21 in every cell resulting in 47 chromosomes instead of the usual 46.

This condition results from unusual cell division which yielded either an egg or a sperm with 24 chromosomes instead of regular 23. When this egg or sperm fuses with regular egg or sperm, the first cell of the developing baby will be 47 chromosomes instead of 46 resulting in a baby with 47 chromosomes.